1. Field
The disclosure relates to signal processing, and in particular, to a system for adaptive gain adjustment in a signal processing path to enhance dynamic range and lower power consumption.
2. Background
Signal processing paths in modern electronic systems may include a digital processing section, a data converter, and an analog processing section. Examples of such systems include audio processing systems wherein an audio signal is digitally processed prior to conversion to an analog signal, other media processing systems, as well as various types of control systems. Typically, the digital section may include a digital signal processor (DSP) adapted to receive an digital input signal and apply various types of digital processing, such as filtering, frequency upsampling, and/or other control processing. The output of the digital section may be coupled to a digital-to-analog converter (DAC) to convert the processed digital signal to an analog signal. The analog section may further include processing blocks such as filters and amplifiers. Typical analog amplifiers may include a power amplifier (PA) to increase the power level of the analog signal to sufficiently drive a subsequent stage.
In the aforementioned signal path, there may be several potential noise sources which may undesirably limit the dynamic range of the processed signals. These include, e.g., digital quantization noise, which includes the quantization noise from the digital input signal as well as any noise shaper used to process the digital signal, DAC circuit noise, and power amplifier circuit noise. Furthermore, several factors may contribute to the overall power consumption of the signal path, including, e.g., digital power consumption from any interpolation filter and/or noise shaper, DAC power consumption, which may depend on the clock rate used for D-to-A conversion, and power amplifier power consumption.
To reduce overall output noise, it may be desirable to pre-amplify the digital signal early in the signal path to provide the signal with sufficient gain to overcome noise from the subsequent stages of the signal path. Any subsequent amplification by analog circuitry may then be correspondingly reduced to maintain a constant overall gain. As a result of applying such gains in the signal path, the overall power consumption required to achieve a given dynamic range for the signal path may be reduced.
It would be desirable to provide efficient techniques for deriving and applying the aforementioned gains in the signal path to reduce noise and power consumption for the overall system.